With the flourishing development of the Internet, in the near future that can be estimated, the IPv4 global unicast address used by the global Internet user at present will be exhausted progressively; and with the growing up of the concept of the Ubiquitous Network and the construction demand of the Internet of Things in the global range, the IPv6, as the major network layer technology of the Next-Generation Internet (abbreviated as NGI), is gradually getting into the role.
In order to deploy rapidly in the evolution process to the IPv6, the IETF has provided the slight-technology-level dual stack-lite (DS-LITE) based on the tunnel and the IPv6 rapid deployment (6rd), and both kinds of technologies use the tunnel technology.
The DS-LITE provides the method for bearing the IPv4 data service by using the IPv6 tunnel; one end of the DS-LITE can be in the home gateway, and the other end locates at the boundary of the IPv4/IPv6. The DS-LITE is not limited to the connection way of the IPv6, and can access through the ways, such as, the Point to Point protocol over Ethernet (PPPoE) or the IP over Ethernet (IPoE), etc., while for the IPv4 client within the tunnel, it has no regulation on how to obtain the DNS yet. As to the 6rd, the tunnel of the IPv4 is used to bear the IPv6 data service, one end of the 6rd can be in the home gateway, and the other end locates in the boundary of the IPv4/IPv6; as to the IPv6 client within the tunnel, there is a scheme supporting the DNS Server carrying the IPv6 by expanding the DHCPv4 protocol now, thus configuring the DNS server of the 6rd corresponding to the IPv6.
To obtain the DNS server by using the Dynamic Host Configuration Protocol (DHCP), it must support the DHCP protocol; if in the situation that it does not support the DHCP protocol, the home gateway based on the tunnel way is unable to obtain the DNS server.